What needs to be changed in a theme, 3.0.4->3.0.5

I need to adapt a theme from 3.0.4 to 3.0.5 and I'm not even certain where to begin.
The weird part is that if I go into tools-interface and change to theme it works until I login (haven't tried everything, but most things do seem to work) when it states that it is not compatible.

I'd love some documentation and I'd love some quick way to just change the parameters in the theme.

I wasn't the designer of the original theme, it was my predecessor.

I'm a novice on php/html/css/jquery but I've dabbled with it through the years, but I'm a full time techie, so I'm not afraid to learn stuff naturally.

You have to add an ispconfig_version file to the theme. A lot of the other template files have changed as well, but the error that you are seeing is due to you not having that file. you need to place the version of ISPConfig that your theme is compatible with.